Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 061330
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST MON JUL 6 2015

.SYNOPSIS...
TRADE WINDS WILL INCREASE THROUGH THE WEEK AS HIGH PRESSURE BUILDS
IN NORTH OF THE AREA. CLOUDS AND PASSING SHOWERS WILL FAVOR WINDWARD
AND MAUKA AREAS BUT MOST SHOWERS ARE EXPECTED TO BE LIGHT AND BRIEF.

&&

.DISCUSSION...
THERE IS LITTLE CHANGE IN OVERALL FORECAST PHILOSOPHY FROM LAST
EVENING. HOWEVER...WE ARE TRANSITIONING TO A TRADE WIND PATTERN A
BIT FASTER THAN ANTICIPATED. TROUGHING TO THE NORTH AND WEST OF THE
MAIN HAWAIIAN ISLANDS CONTINUES TO LIFT NORTHWARD THIS
MORNING...ALLOWING THE SUBTROPICAL RIDGE TO OUR NORTHEAST TO REBOUND
WESTWARD. THIS IS STEEPENING THE PRESSURE GRADIENT ACROSS OUR AREA
RESULTING IN STEADILY INCREASING EASTERLY TRADE WINDS. AN ASCAT PASS
LAST EVENING SHOWED WIND SPEEDS HAD ALREADY REACHED INTO THE 15 TO
20 MPH RANGE. OVERNIGHT SOUNDINGS SHOW PERSISTENT SUBSIDENCE
INVERSIONS WITH BASES AROUND 5000 FEET ALONG WITH CAPE OF LESS THAN
400 J/KG. SATELLITE LOOP SHOWS PATCHES OF BROKEN LOW CLOUDS MOVING
IN ON THE TRADES TOWARDS MAUI AND THE BIG ISLAND...AND CLOUD COVER
ACROSS THE ISLANDS HAS ALREADY BEGUN TO ASSUME A FAMILIAR TRADE WIND
DISTRIBUTION FAVORING WINDWARD AREAS. HOWEVER...RADAR SHOWS VERY
LITTLE SHOWER ACTIVITY ACROSS THE AREA...LIKELY A TESTAMENT OF OUR
RATHER STABLE AND DRIER THAN CLIMO AIR MASS.

TRADE WINDS WILL CONTINUE TO STRENGTHEN INTO THE MIDDLE OF THE WEEK
AS HIGH PRESSURE GRADUALLY BUILDS IN NORTH OF THE AREA. CLOUDS AND
PASSING SHOWERS WILL TEND TO FAVOR WINDWARD AND MAUKA AREAS BUT MOST
SHOWERS ARE EXPECTED TO BE LIGHT AND BRIEF. MOST LEEWARD AREAS WILL
REMAIN DRY WITH JUST A FEW SHOWERS POSSIBLE OVER LEEWARD AREAS OF
THE BIG ISLAND DURING THE AFTERNOON AND EVENING HOURS. TOWARD THE
MIDDLE OF THE WEEK TRADE WINDS WILL BE SUFFICIENTLY STRONG ENOUGH TO
BLOW A FEW PASSING SHOWERS OVER TO SELECT LEEWARD AREAS OF THE
SMALLER ISLANDS. A SMALL CRAFT ADVISORY IS NOW IN EFFECT THROUGH
EARLY WEDNESDAY MORNING FOR THE TRADITIONALLY WINDY AREAS AROUND
MAUI AND THE BIG ISLAND.

THE CENTRAL PACIFIC HURRICANE CENTER IN HONOLULU AND THE NATIONAL
HURRICANE CENTER IN MIAMI ARE MONITORING AN AREA OF DISTURBED
WEATHER OVER THE EAST PACIFIC. THIS AREA WILL CONTINUE TO BE CLOSELY
MONITORED FOR ANY SIGNS OF DEVELOPMENT. CONFIDENCE IN THE LONG RANGE
FORECAST FOR NEXT WEEKEND IS RATHER LOW AT THE PRESENT TIME. THE
CURRENT EXTENDED FORECAST KEEPS US IN A TRADE WIND REGIME WITH A
WEAK TROUGH OF LOW PRESSURE EMBEDDED IN THE TRADES. THIS COULD
CHANGE DEPENDING ON WHETHER OR NOT A SYSTEM DEVELOPS AND ON ITS
FUTURE TRACK AND INTENSITY.

&&

.AVIATION...
BROKEN LOW CLOUDS WITH EMBEDDED SHOWERS WILL BE PASSING THROUGH THE
ISLANDS THROUGH MID MORNING...AFFECTING PRIMARILY THE WINDWARD AND
MOUNTAIN AREAS WITH TEMPO MVFR CONDS. COVERAGE OF THESE CLOUDS AND
SHOWERS WILL NOT BE WIDESPREAD ENOUGH TO WARRANT AIRMET SIERRA FOR
MTN OBSCURATION...HOWEVER. EXPECT LESS SHOWERS...AND CLOUDS BY NOON.

THE KONA AND KAU SLOPES WILL HAVE THEIR NORMAL CLOUD BUILDUP DURING
THE LATE MORNING AND EARLY AFTERNOON HOURS...WITH BRIEF MVFR CIGS
AND VIS FROM THE ISOL SHOWERS.

THE TRADE WINDS WILL BE STRENGTHENING AS THE DAY PROGRESSES...LIKELY
REQUIRING AN AIRMET TANGO STARTING WITH THE 22Z PACKAGE.

&&

.MARINE...
TRADE WINDS ARE RECOVERING MORE QUICKLY THAN EXPECTED...AND MODELS
ARE STRONGLY SUGGESTING SMALL CRAFT ADVISORY CONDITIONS MAY OCCUR AS
EARLY AS THIS AFTERNOON FOR THE TRADITIONALLY WINDY WATERS AROUND
MAUI AND THE BIG ISLAND. A SMALL CRAFT ADVISORY FOR THESE AREAS IS
THEREFORE IN EFFECT THROUGH EARLY WEDNESDAY MORNING. THIS ADVISORY
MAY HAVE TO BE EXTENDED AS TRADE WINDS CONTINUE TO STRENGTHEN
THROUGH THE WEEK.

THE CURRENT SOUTH SWELL WILL CONTINUE TO LOWER TODAY. ANOTHER SWELL
IS EXPECTED TO FILL IN TONIGHT AND TUESDAY. SURF HEIGHTS MAY ONCE
AGAIN APPROACH LOW END ADVISORY LEVELS. WE WILL CONTINUE TO MONITOR
BUOY DATA FOR SIGNS OF THIS NEW SWELL. OTHERWISE A SMALL NORTHWEST
SWELL IS EXPECTED TO LINGER INTO THE MIDDLE OF NEXT WEEK PROVIDING
FOR SOME SMALL RIDEABLE WAVES ALONG EXPOSED SHORELINES.
STRENGTHENING TRADE WINDS WILL CAUSE SHORT PERIOD CHOPPY SURF TO
INCREASE THIS WEEK ALONG EAST FACING SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY THROUGH 6 AM HST WEDNESDAY FOR ALENUIHAHA AND
PAILOLO CHANNELS...MAALAEA BAY AND WATERS SOUTH OF THE BIG ISLAND.

&&

$$

SYNOPSIS/DISCUSSION/MARINE...POWELL
AVIATION...LAU







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